<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
	</head>
	<body>
	    <div id="app">
	        <input type="text" id="txt">
	        <p id="show"></p>
	    </div>
	</body>
	<script type="text/javascript">
	    var obj = {};
	    Object.defineProperty(obj, 'txt', {
	        get: function () {
	            return obj
	        },
	        set: function (newValue) {
	            document.getElementById('txt').value = newValue;
	            document.getElementById('show').innerHTML = newValue;
	        }
	    })
	    document.addEventListener('keyup', function (ev) {
	        obj.txt = ev.target.value;
	    })
	</script>
</html>
